Compositions for compounding foamable, fluropolymer pellets for use in melt processing cellular or foamed fluoropolymer applications

ABSTRACT

The disclosure provides a composition as well as a set of compositions and method for producing cellular or foamed or blown fluoropolymers such as perfluoropolymers and other thermoplastics articles allowing for the creation of a lower cost communications cable, conductor separator, conductor support-separator, jacketing, tape, wire insulation and in some cases a conduit tube as individual components or combined configurations that exhibit improved electrical, flammability and optical properties. Specifically, the foamable or blown fluoropolymer such as a perfluoropolymer cellular insulation composition comprises; talc and the selected fluoropolymer such as perfluoropolymers. Compounded pellets or products resulting in cellular or foamable products using these pellets has also been realized by providing the melt combination in the pellets of only talc and a perfluoropolymer.

RELATED APPLICATIONS

The present application is a national-stage filing under 35 U.S.C. §371of PCT International Application PCT/US2008/009285, titled “Compositionsfor Compounding and Extrusion of Foamed Fluoropolymers”, filed 1 Aug.2008, which claims priority to U.S. Provisional Patent Application No.60/963,322, titled “Compositions for Compounding and Extrusion of FoamedFluoropolymers for Wire and Cable Applications”, filed 3 Aug. 2007.

The present application also claims priority under 35 U.S.C. §120 fromU.S. patent application Ser. No. 12/221,280, titled, “Compositions forCompounding, Extrusion and Melt Processing of Foamable and CellularFluoropolymers”, filed 1 Aug. 2008; PCT International Application No.PCT/US2008/009286, titled “Compositions for Compounding, Extrusion andMelt Processing of Foamable and Cellular Fluoropolymers,” filed 1 Aug.2008 and each of which also takes original priority from both U.S.Provisional Application No. 60/963,322, titled “Compositions forCompounding and Extrusion of Foamed Fluoropolymers for Wire and CableApplications”, filed 3 Aug. 2007 and U.S. Provisional Application No.60/953,729, titled “Perfluoropolymer Foamable Composition”, also filed 3Aug. 2007.

Each of these references is hereby expressly incorporated by referenceherein in its entirety.

FIELD OF INVENTION

Wire and cable applications, especially those using copper conductors,utilize the insulative properties of specific polymers over theconductors as insulation and over the entire cable core of insulatedconductors as jackets. Cable fillers of varying shapes and size are usedas well for their insulative properties and more specifically incommunications designs to minimize pair-to-pair crosstalk within a cableas will as mitigating crosstalk between adjacent cables which iscommonly referred to as “alien crosstalk.” Jackets and cable fillersprovide mechanical and physical properties as well as an ever evolvingrequirement for enhanced fire performance i.e. (reduced flame spread,ignitability, and smoke evolution.) These mechanical, physical and fireretardancy performance requirements apply to fiber optic cables as well.Cable design demands a balance of these performance requirements and theattributes of processing, e.g., extruding a cellular foamedfluoropolymer (such as a perfluoropolymer) that improves both insulationvalues e.g. (lower crosstalk in communications cables) while loweringmaterial content and therefore the amount of combustible materials usedin a cable. These added performance characteristics through cellular (ormicrocellular) foaming can additionally lower cost of the overall cabledesign.

BACKGROUND OF INVENTION

Communication cables have evolved continuously over the years as we haveevolved from a voice-based telecommunication network environment to thenew structured cabling designs for high-speed data transmission whichare commonly referred to as Local Area Networks or LAN's. Technicalrequirements, standards and guidelines of the Telecommunication IndustryAssociation and Electronic Industry Association (TIA/EIA) andInternational Standard Organization (ISO) have been developed andpublished to support high-speed data communication of voice, interne andvideo. In addition, these requirements continue to evolve with more andmore stringent electrical performance needs such that cellular foaminsulation and fillers play an increasing role in the cable designs. Theprimary communications cable designs incorporate twisted copper pairstogether to form a balanced transmission line, coaxial cables, and fiberoptic cables. All of these cables may be run in a network of a building(LAN's) as separate functional cables or in hybrid or combination cabledesign.

Furthermore, TIA/EIA has defined standards that are published andrecognized as well as industry drafts of soon-to-be published standardsfor commercial building telecommunication networks. Table 1, whichfollows, provides those published and pending, or soon-to-be adopted andpublished Technical Service Bulletin “TSB” standards.

TABLE 1 TIA/EIA Standards Category 5e Frequency BandwidthANSI/TIA/EIA-568-A ISO Class D 1 to 100 mhz Commercial BuildingTelecommunications Standard Part 2: Balanced Twisted Pair CablingComponent; 2001 Category 6 Frequency Bandwidth ANSI/TIA/EIA-568-B.2-1ISO Class E 1 to 250 mhz Commercial Building Telecommunications StandardPart 2: Addendum 1: Transmission Specification for 4 pair 100 ohmCategory 6 Cabling; 2002 Category 6A Frequency BandwidthANSI/TIA/EIA-568-B.2-10 ISO Class E_(A) 1 to 500 mhz Commercial BuildingTelecommunications Standard Part 2: Addendum 10: TransmissionSpecification for 4 Pair 100 ohm Augmented Category 6 Cabling; TSBpending publication Category 7 Frequency Bandwidth TIA not activelydeveloping standard; ISO Class F 1 to 600 mhz ISO/EIA-11801, 2^(nd) Ed.Information Technology—Generic Cabling for Customer Premises, 2002

Each of the standards of Table 1 illustrates continued widened bandwidthenabling greater data transmission. The broadening of communicationcable bandwidth enhances the electrical characteristics or data bit ratebased on the evolving needs of software, hardware and videotransmission. The terminology within the standards for testing can bedefined as electrical performance within the cable as measured byimpedance, near end and far end crosstalk (NEXT & FEXT), attenuation tocrosstalk ratio (ACR), ELFEXT, ELNEXT, Power Sum, etc., and theelectrical performance that may be transferred to the adjacent cablea.k.a. (alien cross talk) which are measured within similar performanceparameters while incorporating a power sum alien cross talk requirement.

Electromagnetic noise that can occur in a cable that runs alongside oneor more cables carrying data signals can create alien crosstalk. Theterm “alien” arises from the fact that this form of crosstalk occursbetween different cables in a group or bundle, rather than betweenindividual wires or circuits within a single cable. Alien Crosstalk canbe particularly troublesome because of its effect on adjacent 4 paircables which degrades the performance of a communications system byreducing the signal-to-noise ratio. Traditionally, alien crosstalk hasbeen minimized or eliminated by aluminum Mylar® shields and/or braid inshielded cable designs i.e. (Category 7 or ISO Class F shielded designs)to prevent electromagnetic fields from ingress or egress from the cableor cables. The use of foamed or blown constructions for symmetrical andasymmetrical airspace designs further improve electrical performancecharacteristics in that the overall modulus and elasticity of theresulting foamed compounds are reduced leading to final conformationsthat more closely approach optimal geometries. Specifically, the abilityto form inner structures of cables such that these inner structures havelittle or no plastic memory once the cabling process is completed,ensures that the nested pairs remain in the desired geometricconfiguration and that the use of foamed fillers, insulations andjackets using air as an insulator act to mitigate alien crosstalk inUnshielded Twisted Pair (UTP) designs i.e. (Category 6 or ISO Class Eand Category 6 Augmented or ISO Class E_(A)).

These Electrical Performance Standards especially for UTP cables(Category 5e, 6, 6A and 7) necessitate improved insulative performancewherein foamed fluoropolymers optimize their inherently excellentinsulative values i.e. (dielectric constant and dissipation factor.)Foamed fluoropolymers (such as perfluoropolymers) offer lower cost andlower material content while improving fire retardancy performance bylowering the amount of combustible material in a cable and the overallfire load of Local Area Network cables within a building.

A brief review of the Fire Performance Requirements both in NorthAmerica and Globally follows:

In 1975, the National Fire Protection Agency (NFPA) recognized thepotential flame and smoke hazards created by burning cables in plenumareas, and adopted within the United States, the National Electric Code(NEC), and a standard for flame retardant and smoke suppressant cables.This standard, commonly referred to as “the Plenum Cable Standard”, waslater adopted for North America Communications Cabling by Canada andMexico. The standard permits the use of power-limited type cables thatincludes communication cables without conduit, so long as the cableexhibits low smoke and flame retardant characteristics. The test methodfor measuring these characteristics is commonly referred to as theSteiner Tunnel Test. The Steiner Tunnel Test has been adapted for theburning of cables according to the following test protocols: NFPA 262,Underwriters Laboratories (U.L.) 910, or Canadian Standards Association(CSA) FT-6. The test conditions for each of the U.L. 910 Steiner TunnelTest, CSA FT-6, and NFPA 262 are as follows: a 300,000 BTU/hour flame isapplied for 20 minutes to a calculated number of cable lengths based ontheir diameter that fills a horizontal tray approximately 25 feet longwith an enclosed tunnel. This test simulates the horizontal areas(ceilings) in buildings wherein these cables are run.

The criteria for passing the Steiner Tunnel Test UL 910/NFPA 262 are asfollows:

-   -   A. Flame spread—a maximum flame spread of less that 5.0 feet.    -   B. Smoke generation:        -   1. A maximum optical density of smoke less than 0.5.        -   2. An average optical density of smoke less than 0.15.

The premise of the standard is based on the concerns that flame andsmoke could travel along the extent of a building plenum area if theelectrical conductors and cable were involved and were not flame andsmoke resistant. The National Fire Protection Association (“NFPA”)developed the standard to reduce the amount of flammable materialincorporated into insulated electrical conductors and jacketed cables.Reducing the amount of flammable material would, according to the NFPA,diminish the potential of the insulating and jacket materials fromspreading flames and evolving smoke to adjacent plenum areas andpotentially to more distant and widespread areas within a building. Thecellular foamable fluoropolymer products of this disclosure cantypically reduce the quantity of combustible materials by 30 to 60percent based on the extent of the foaming process within insulations,fillers and jacket materials.

The products of the present disclosure have also been developed tosupport the possible adoption of a new NFPA standard referenced as NFPA255 entitled “Limited Combustible Cables” with less than 50 as a maximumsmoke index and NFPA 259 entitled “Heat of Combustion” which includesthe use of an oxygen bomb calorimeter that allows for materials withless than 3500 BTU/lb. for incorporation into cabling systems andbuildings wherein survivability of the communication network from firesis required i.e. (military installation such as the Pentagon inWashington D.C.).

For these applications requiring survivability from flame spread andsmoke generation, the cellular products of the present disclosure willbe an effective method for reducing material content and the fuel loadof cables in such critical environments.

Table 2 provides a hierarchy of fire performance standards for NorthAmerica and Europe.

TABLE 2 Flammability Test Methods and Level of Severity for Wire andCable Cable Type Test Method Ignition Source Output Duration LimitedUL2424/NFPA 8,141 KJ/kg 10 min. Combustible 259/255/UL723 (3,500BTU/lb.) CMP Steiner Tunnel 88 kW (300 k BTU/hr.) 20 min. UL 910/NFPA262 CMR RISER 154 kW (527 k BTU/hr.) 30 min. UL 1666/UL2424/NFPA 259 CPDSingle Burning Item 30 kW (102 k BTU/hr.) 30 min. Class D (20 minburner) CPD Modified IEC 60332-3 30 kW (102 k BTU/hr.) 20 min. Class D(Backboard behind ladder (heat impact)) CM IEC 60332-3 20.5 kW (70 kBTU/hr.) 20 min. CMX Vertical Tray 20.5 kW (70 k BTU/hr.) 20 min. CMUCIEC 60332-1/ULVW-1 Bunsen Burner  1 min. (15 sec. Flame) Cable FirePerformance (Levels of Severity) NFPA 255 & NFPA 259/LC/CPD Class B1+/UL2424 (most stringent) NFPA 262/EN 50289/FT-6/CPD Class B1/UL 910 | UL1666 Riser/FT-4/CPD Class C & B2 | UL 1581 Tray/IEC 60332-3/FT-2/CPDClass D | VW 1/IEC 60332-1/FT-1/CPD Class E (least stringent)

SUMMARY OF THE INVENTION

In the present disclosure the term blowing agent(s), foaming agent(s),are synonymous and may be used interchangeably and are associated withchemical reactions. The term nucleating agent(s) are used in materialsthat provide sites for the formation of cells resulting from thechemical reaction of the blowing agents or the use of gas injection.

The present disclosure provides for the use of talc or talc derivativeswhich are natural or synthetic hydrated magnesium silicate compound.Talc (derived from the Persian talc via Arabic talq) is a mineralcomposed of hydrated magnesium silicate with the chemical formulaH₂Mg₃(SiO₃)₄ or Mg₃Si₄O₁₀(OH)₂

The present disclosure refers to talc as natural or synthetic hydratedmagnesium silicate. It has been discovered that talc acts independentlyas a chemical blowing agent in combination with the fluoropolymers (suchas perfluoropolymers) of the present invention without the need foradditional blowing agents, foaming agents or the need for any othernucleating agent. In certain cases, the talc is compounded into solidfluoropolymer pellets or fluorinated polymeric foamable pellets (in theform of one or more pellets) from which foamed products may be obtainedby extrusion or injection molding, wherein the pellets containing talcact as a chemical blowing agent and in some cases as a nucleating agentwhen the pellets are heated and extruded.

The embodiments within this disclosure reference talc as a chemicalblowing agent as well as a nucleating agent except where otherwisenoted. The use of talc in combination with the use of a chemical blowingagent or gas injection is also included in the scope the presentdisclosure.

This disclosure provides a composition, method and system forcompounding foamable pellets from fluorinated polymers (eitherfluoropolymers (such as perfluoropolymers) and furthermore thesefoamable pellets may be extruded to create a lower cost communicationscable, conductor separator, conductor/cable support-separator,jacketing, tape, tube, crossweb, wrap, wire insulation and as well as aconduit tube for individual components or any communications cables,conductor separators, cable support-separators, wire insulation andseveral combined configurations that exhibit improved electrical,flammability and optical properties.

The foamable fluoropolymers (such as perfluoropolymers) disclosed yieldthe inherent benefits of reducing the amount of combustible materialswithin a cable as well as enhancing electrical properties while reducingcosts. The blown, foamed or cellular fluoropolymers (such asperfluoropolymers) insulation, jacket, or filler material using anucleating/foaming agent of talc the chemical composition of whichincludes MgSiOH; H₂Mg₃(SiO₃)₄; Mg₃Si₄O₁₀(OH)₂; 3MgO+4SiO₂+H₂O;MgOH+H₂O+SiOH; or any derivatives thereof, that synergistically reactswith the fluoropolymers (such as perfluoropolymers) at their elevated orhigher extrusion operating temperatures with or without a chemicalblowing agent such as magnesium carbonate, calcium carbonate, and amixture of both magnesium carbonate and calcium carbonate. Thenucleating/foaming agent capabilities of talc creates a foam ideallysuited for the requirement of Category 6 and 6A UTP insulation, jacket,or and tapes and is highly cost effective at approximately $1.00 per lb.as a replacement for the traditionally used Boron Nitride (nucleatingagent) that costs approximately $60.00 per lb. The talc (a chemicalblowing agent and it may also act as a nucleating agent), costsignificantly less than $1.00 per lb when purchased in largerquantities.

The reduction in cost from changing Boron Nitride to talc is one of manybenefits. Another benefit of using talc is that insulation, jacketingand filler extrusion may be performed by a relatively simplistic androbust chemical reaction that uses varying extrusion temperatures tofoam at various rates or percentages which are desired based on varyingtalc loadings. Noteworthy, under specific extrusion conditions that aredescribed in further detail, talc itself “foams”. Traditional foaming offluoropolymers (such as perfluoropolymers) has been via a gas injectionextrusion process and the use of nucleated fluoropolymers (such asperfluoropolymers) with Boron Nitride. The cost benefits of chemicalfoaming vis-à-vis gas foaming of fluoropolymers (such asperfluoropolymers) enable standard high temperature extruders to runfoam fluoropolymers (such as perfluoropolymers) without the need to portthe barrel with a highly sophisticated gas valve, as well as the designand use of a specialized compression screw. The use of talc as anucleating agent also works effectively or as a partial or completereplacement for Boron Nitride.

An added benefit of using talc which is either alkali or base is that itneutralizes the acidity of hydrogen fluoride (HF) which may evolveduring extrusion. HF is highly acidic and causes corrosion in extrusionbarrels, screws and extrusion head, tools and dies. Traditional metalsor non-Hasteloy or Inconel surfaces cannot be used to extrudefluoropolymers (such as perfluoropolymers) under normal processconditions and the use of talc significantly reduces the acidity of theHF, thus mitigating corrosive wear on standard extrusion equipment.

The introduction of talc has the benefit of being an acid (HF) scavengerwhen compounded into pellets prior to extrusion and acts as both anucleating as well as a foaming agent. Furthermore, when enhanced withthe addition of a pelletized fluoropolymers (such as perfluoropolymers)with MgCO₃ and CaCO₃ and AClyn® wax (a registered trademarked waxprovided by Honeywell) fluoropolymers (such as perfluoropolymers)foaming levels are further enhanced. This foaming agent of magnesiumcarbonate and calcium carbonate may be added as a separate pellet in atumble blended mix or compounded together in a single homogenous pelletof talc (MgSiOH) and MgCO₃/CaCO₃/AClyn wax. The single homogenous pelletcan then be extruded for communication cables, conductor separators,cable support-separators, wire insulation, jacketing, wraps, tapes,conduit tubes or any combination of said communications cables,conductor separators, cable support-separators, wire insulation, orfillers in a very simplistic chemically foamed extrusion process forfluoropolymers (such as perfluoropolymers). The foaming rate from 15percent to 50 percent can be raised or lowered based on the percentageof each constituent used as well as by adjustments in extrusiontemperatures, and screw design.

The present disclosure provides for the use of fluoropolymers and/orperfluoropolymers in any amount and in any combination. The family offluoropolymers (such as perfluoropolymers) wherein these compoundednucleating and foaming agents may be used is at least the following:

-   -   The fluoropolymers that are characterized here are the melt        processable materials for which this disclosure is focused:    -   1. MFA (Polytetrafluoroethylene-Perfluoromethylvinylether)    -   2. FEP (Fluorinated Ethylene Propylene)    -   3. PFA (Perfluoroalkoxy)    -   4. PTFE (Polytetrafluoroethylene    -   5. ETFE (Ethylene tetrafluoroethylene or        (poly(ethylene-co-tetrafluoroethylene))    -   6. ECTFE (Ethylene chlorotrifluoroethlyene)    -   7. PVDF (Polyvinylidene Fluoride)    -   The perfluoropolymers that are characterized here are the melt        processable materials for which this disclosure is focused:    -   1. FEP (Fluorinated Ethylene Propylene)    -   2. PFA (Perfluoroalkoxy)    -   3. MFA (Polytetrafluoroethylene-Perfluoromethylvinylether)    -   4. PTFE (Polytetrafluoroethylene)

It should be emphasized that the use of talc may be independent of theuse of MgCO₃/CaCO₃/AClyn wax or talc may be used in any combination withMgCO₃/CaCO₃/AClyn wax to produce the desired foamed compositions.

The perfluoropolymers described are fluoropolymer resins that can beused and include copolymers of TFE with one or more copolymerizablemonomers chosen from perfluoroolefins having 3-8 carbon atoms andperfluoro (alkyl vinyl ethers) (PAVE) in which the linear or branchedalkyl group contains 1-5 carbon atoms. Preferred perfluoropolymersinclude copolymers of TFE with at least one hexafluoropropylene (HFP)unit and one PAVE (unit). Preferred comonomers include PAVE in which thealkyl group contains 1-3 carbon atoms, especially 2-3 carbon atoms, i.e.perfluoro (ethyl vinyl ether) (PEVE) and perfluoro (propyl vinyl ether)(PPVE). Additional fluoropolymers that can be used include copolymers ofethylene with TFE, optionally including minor amounts of one or moremodifying comonomer such as perfluorobutyl ethylene. Representativefluoropolymers are described, for example, in ASTM StandardSpecifications D-2116, D-3159, and D-3307. Such fluoropolymers arenon-functional fluoropolymers if they have essentially no functionalgroups, but are functionalized fluoropolymers if functional groups areadded, e.g., by gaffing. Alternatively or additionally, preferredfluoropolymers are non-elastomeric, as opposed to elastomeric.

Functionalized fluoropolymers include fluoropolymers such as thosedescribed in the foregoing paragraph and additionally containingcopolymerized units derived from functional monomers. If theconcentration of functional monomer is high enough in a TFE copolymer,however, no other comonomer may be needed. Usually, but not necessarily,the functional groups introduced by such monomers are at the ends ofpendant side groups. Functional monomers that introduce pendant sidegroups having such functionality can have the general formula CYZwherein Y is H or F and Z contains a functional group. Preferably, eachY is F and —Z is —Rf—X, wherein Rf is a fluorinated diradical and X is afunctional group that may contain CH2 groups. Preferably, Rf is a linearor branched perfluoroalkoxy having 2-20 carbon atoms, so that thefunctional comonomer is a fluorinated vinyl ether. Examples of suchfluorovinylethers include CF₂CF[OCF₂CF(CF₃)]m-O—CF₂)n CH₂OH as disclosedin U.S. Pat. No. 4,982,009 and the alcoholic esterCF₂—CF[OCF₂CF(CF₃)]m-O—CF₂)n-(CH₂)p-O—COR as disclosed in U.S. Pat. No.5,310,838. Additional fluorovinylethers includeCF₂CF[OCF₂CF(CF₃)]mO(CF₂)n COOH and its carboxylic esterCF₂CF[OCF₂CF(CF₃)]mO(CF₂)nCOOR disclosed in U.S. Pat. No. 4,138,426. Inthese formulae, m=0-3, n=1-4, p=1-2 and R is methyl or ethyl. Preferredfluorovinylethers include CF₂CF—O—CF₂CF₂—SO₂F;CF₂CF[OCF₂CF(CF₃)]0(CF₂)₂—Y wherein —Y is —SO₂F, —CN, or —COOH; andCF₂.CF[OCF₂CF(CF₃)]O(CF₂)₂—CH₂—Z wherein —Z is —OH, —OCN, —O—CO)—NH₂, or—OP(O)(OH)₂. These fluorovinylethers are preferred because of theirability to incorporate into the polymer backbone and their ability toincorporate functionality into the resultant copolymer.

In one embodiment, a foamable composition can include at least onefluoropolymer and a chemical agent capable of functioning as both anucleating agent and a foaming agent. In this embodiment, the chemicalagent constitutes the only foaming agent present in the foamablecomposition. For example, the chemical agent can include talc or anytalc derivative. In another example, the chemical agent can consistessentially of talc or any talc derivative.

In some embodiments, the chemical agent can be present in aconcentration range of up to about 50 percent by weight of said foamablecomposition. In other embodiments, the chemical agent can comprise about7.5 percent by weight of said foamable composition.

The chemical agent, such as talc or any talc derivative, can be capableof functioning as both a nucleating agent and a foaming agent uponextrusion of said foamable composition at a temperature greater thanabout 525 degrees F. In some embodiments, the chemical agent can becapable of functioning as both a nucleating agent and a foaming agent ofthe foamable composition. The chemical agent can also allow forprocessing of the foamable composition at a temperature of up to about30 degrees F. below conventional temperatures normally required duringextrusion of conventional foamable compositions having the at least onefluoropolymer. For example, the chemical agent can act as a processingaid to reduce or eliminate melt fracture during processing of saidfoamable composition.

In another embodiment, a foaming composition can include at least onefluoropolymer in a molten state at an elevated temperature and achemical agent dispersed in the molten fluoropolymer. The chemical agentcan be capable of functioning as both a nucleating agent and a foamingagent and can constitute the only foaming agent present in the foamingcomposition. For example, the elevated temperature of the molten stateof the fluoropolymer can be sufficient to cause the at least onechemical agent to foam. In other embodiments, the elevated temperaturecan be, for example, any temperature in which the fluoropolymer is in amolten state, for example, the elevated temperature can be greater than340 degrees F., such as about 570 degrees F. to about 600 degrees F. Insome embodiments, e.g., for lower melting fluoropolymers, the elevatedtemperature can be in the range of about 430 degrees F. to about 530degrees F. In other embodiments, the elevated temperature can be in arange of about 490 degrees F. to about 530 degrees F.

Methods of manufacturing a foamable composition are also provided. Inone embodiment a method includes forming a mixture comprising a blend ofa chemical agent capable of functioning as both a nucleating agent and afoaming agent and at least one base fluoropolymer using thermal andmechanical energy at a processing temperature below a temperature atwhich foaming of the mixture occurs, and processing the mixture to forma foamable composition. In some embodiments, the chemical agent canconstitute the only foaming agent present in the mixture. In someembodiments, the foamable composition can be further processed to form afoamed article.

In one embodiment, the foamable composition comprises at least onefluoropolymer, at least one magnesium silicate compound, and a foamingagent; where the foaming agent is present in a concentration range ofabout 0.1 percent to about 10 percent by weight of the foamablecomposition.

One embodiment is the use of talc at 7 percent by weight combined with93 percent neat resin (fluoropolymer or perfluoropolymer). In thepresent application talc is referred to as both a chemical agent and afoaming agent and the terms have been used interchangeably.

One embodiment is that foaming in a composition will occur with the useof talc at 10 percent by weight with 90 percent by weight of the neatresin.

In a particular embodiment, at least one magnesium silicate compoundincludes talc or any talc derivative.

In a particular embodiment, at least one magnesium silicate compoundcomprises at least one hydrated magnesium silicate compound.

In one embodiment, at least one magnesium silicate compound is presentin a concentration range of up to about 50 percent by weight of thefoamable composition.

In a particular embodiment, at least one magnesium silicate compoundcomprises about 7.5 percent by weight the foamable compound.

In a particular embodiment, at least one magnesium silicate compoundcomprises about 6 percent by weight of the foamable composition and thefoaming agent comprising of magnesium carbonate and calcium carbonatecombined comprises about 0.4 percent by weight the foamable composition.

In a particular embodiment, magnesium carbonate comprises about 0.3percent to about 3 percent by weight the foamable composition and thecalcium carbonate comprises about 0.1 to about 1 percent by weight ofthe foamable composition.

In a particular embodiment, at least one magnesium silicate compoundcomprises about 6 percent by weight the foamable composition and themagnesium carbonate comprises about 1 percent by weight of the foamablecomposition.

In a particular embodiment, at least one magnesium silicate compoundcomprises a sufficient weight percentage of the magnesium silicatecompound that together with a sufficient weight percentage of onlycalcium carbonate forms the foamable composition.

In one embodiment the foamable composition is in the form of one or morepellets and the pellets are capable of being processed to form a foamedarticle.

In one embodiment the foamable composition is capable of being combinedwith an additional of at least one fluoropolymer and the combination iscapable of being processed to form a foamed article.

In a preferred embodiment the foamable composition comprises at leastone fluoropolymer, talc and any talc derivative, and an additionalfoaming agent where the foaming agent is present in a concentrationrange of about 0.1 percent to about 10 percent by weight of the foamablecomposition.

In a preferred embodiment the foaming composition comprises at least onefluoropolymer in a molten state at an elevated temperature, at least onemagnesium silicate compound dispersed in the molten fluoropolymer, and afoaming agent dispersed in the molten fluoropolymer; where the elevatedtemperature is sufficient to activate the foaming agent and where thefoaming agent is present in a concentration range of about 0.1 percentto about 10 percent by weight of the foaming composition.

In a particular embodiment, the elevated temperature to activate thefoaming agent is greater than 525 degrees F.

In one embodiment the chemical agent is capable of functioning as both anucleating agent and a foaming agent of the foaming composition andwhere the chemical agent allows for processing at a temperature of up to30 degrees F. below the conventional temperatures normally requiredduring extrusion of the foaming composition.

Another added benefit of using talc is that it neutralizes the acidityof hydrogen fluoride (HF) which may evolve during extrusion. HF ishighly acidic and causes corrosion in extrusion barrels, screws andextrusion head, tools and dies. Traditional metals or non-Hasteloy orInconel surfaces cannot be used to extrude perfluoropolymers undernormal process conditions and the use of talc significantly reduces theacidity of the HF, thus mitigating corrosive wear on standard extrusionequipment.

In one embodiment the conventional temperatures are near or above themelting point of at least one fluoropolymer and where the chemical agentacts as a processing aid to reduce or eliminate melt fracture duringprocessing of at least one fluoropolymer.

Pellets of the compounds described above can be created at 430-660degrees F. and under certain conditions as low as 340 degrees F. withinthe extruder barrel.

One embodiment of the present application includes a first compositioncomprising a foaming agent comprising fluoropolymers (such asperfluoropolymers), plus talc or other talc derivative (which mayinclude H₂Mg₃(SiO₃)₄; Mg₃Si₄O₁₀(OH)₂; 3MgO+4SiO₂+H₂O; MgOH+H₂O+SiOH)which is blended, melted and extruded into a solid pelletized form forextrusion that allows for blowing or foaming with or without gasinjection and with or without another chemical foaming agent.

A specific embodiment includes mixtures of a foaming agent comprisingperfluoropolymer pellets (85 percent) and talc (15 percent) which iscompounded together via heating to a selected melting point and extrudedinto a pelletized form, tumble blended in pelletized form for subsequentextrusion such that the pellets are placed in an extruder, heated to aselected melting point allowing for manufacture of blown or foamedinsulative components.

An additional composition may be used exclusively as a foaming agentwith nucleating capabilities in a tumbled blend of 30 percent foamingagent and 70 percent perfluoropolymer pellets.

An additional embodiment includes the composition comprising a singularperfluoropolymer or a mixture of different perfluoropolymers or recycledperfluoropolymers wherein the recycled perfluoropolymers comprise from1-100 percent of the perfluoropolymers.

In another embodiment of the composition, additional nucleating agentmay be used in combination with the talc in an amount from 1 percent to10 percent by weight.

In another embodiment the composition comprises talc in an amount from 2percent-20 percent by weight.

Another embodiment includes the talc of the composition, during blowingor foaming, reacting synergistically with another composition to formsmaller, more uniform cell structures in the foamed or blown othercomposition.

Additionally an embodiment is where the composition comprises 100percent non-recycled talc powder combined with 100 percent non-recycledperfluoropolymer wherein the ratio of talc to perfluoropolymer is 0.5percent-20 percent by weight.

In another embodiment the talc and/or the fluoropolymers (such asperfluoropolymers) may be recycled or virgin.

Another embodiment includes the extruded fourth composition comprising afoamed or blown cell structure wherein the cell structures areconsistent and as small as 0.0005 inches to 0.003 inches with an averagesize of 0.0008 inches.

In another embodiment the foamed cells have a open and closed cellstructure.

In another embodiment the composition comprises talc in an amount from0.5 percent-20 percent by weight wherein the talc and/or fluoropolymers(such as perfluoropolymers) may be recycled materials.

Another added benefit of using talc is that it neutralizes the acidityof hydrogen fluoride (HF) which may evolve during extrusion. HF ishighly acidic and causes corrosion in extrusion barrels, screws andextrusion head, tools and dies. Traditional metals or non-Hasteloy orInconel surfaces cannot be used to extrude perfluoropolymers undernormal process conditions and the use of talc significantly reduces theacidity of the HF, thus mitigating corrosive wear on standard extrusionequipment.

In another embodiment the composition comprises inorganic or organicsalt(s) and fluoropolymers (such as perfluoropolymers).

In another embodiment the cellular insulation is 100 percent recyclable.

Another embodiment is that the composition may comprise either inorganicor organic additives or both that includes inorganic salts, metallicoxides, silica and silicon oxides as well as substituted andunsubstituted fullerenes.

Also in an embodiment the composition is capable of meeting specificflammability and smoke generation requirements as defined by UL 910, UL2424, NFPA 262, 259, 255, and EN 50266-2-x, class B test specifications.

Another embodiment includes the use of a twin-screw extruder formelting, blending and pelletizing the composition. In more detail, thecompounding process utilizes a two-step system to insure the foamingcomponents are thoroughly distributed and dispersed in the base polymerof the final compound. The first step requires a masterbatch blend bemade of the foaming agents. The foaming agents are in a fine powder formand a high intensity blender, (i.e. Henschel type) is used to preparethe powder blend according to the specified formulation. A certainamount of resin, also in powder form, can be used in the first blendingstep as a mechanism to predisperse the foaming agents and aid in thesecond extrusion compounding step. The second stage of the compoundpreparation process utilizes a twin screw extrusion compounding systemto incorporate the foaming agent masterbatch blend with the base resin.The design of the compounding screw is such that there is sufficientheat and mechanical energy to fully thermally melt the base polymer andincorporate the masterbatch blend with proper distribution anddispersion during mixing for homogeneity, but yet mild enough to keepthe processing temperature of the compound below that in which foamingmay be prematurely initiated. The final compound can be strand extrudedand pelletized or alternatively an underwater pelletizing technique maybe used (in other words air or water cooling is acceptable).

In one embodiment the method of manufacturing a foamable compositioncomprises forming a mixture comprising of a blend of a magnesiumsilicate compound, a foaming agent and, at least one base fluoropolymerusing thermal and mechanical energy at a processing temperature below atemperature at which foaming of the mixture occurs; where the foamingagent is present in a concentration range of about 0.1 percent to about10 percent by weight of the mixture and; then processing the mixture toform a foamable composition.

In a particular embodiment, the method of further comprising pelletizingthe extrudate to form a plurality of foamable pellets.

In a particular embodiment, the method where the processing of themixture results in one or more foamable pellets having a solid phasesuch that the foamable pellets are capable of being processed to form afoamed article.

In a particular embodiment, the method where the foamable composition isproduced at a temperature low enough to prevent the foamable compositionfrom foaming.

In a particular embodiment, the method where the temperature issufficiently low so as to thermally constrain the foamable compositionfrom foaming.

In a particular embodiment, the method where processing the foamablecomposition comprises applying energy to the foamable composition.

In a particular embodiment, the method where applying the energy can beany of heat, pressure, or a combination of heat and pressure.

In a particular embodiment, the method where processing the foamablecomposition comprises melt processing.

In a particular embodiment, the method where foamable compositions is ina solid state or a molten state.

In one embodiment, a method for manufacturing a foamed article comprisesproviding a foamable composition including at least one fluoropolymer,at least one magnesium silicate compound and, a foaming agent, where thefoaming agent is present in a concentration range of about 0.1 percentto about 10 percent by weight of the foamable composition and, extrudingthe foamable composition to form a foamed article.

In a particular embodiment, the method where the foamed articlecomprises communications cables, conductor separators, cablesupport-separators, wire insulation, jacketing, wraps, tapes, conduittubes, or any combination of the communications cables, conductorseparators, cable support-separators, wire insulation.

Another embodiment is a method and system for heating the talc powderand a selected pelletized fluoropolymer (such as perfluoropolymer)creating a melt blendable composition, extruding the molten composition,cooling the molten composition and forming the solid composition into apelletized nucleating and foaming agent.

Another embodiment includes a communications cables, conductorseparators, conductor/cable support-separators, jacketing, tapes, wraps,wire insulations, conduit tubes, or any combination of thecommunications cables, conductor separators, cable support-separators,wire insulation individually comprising the same blown or foamedcomposition or may utilize the composition that includes selectedfluoropolymers (such as perfluoropolymers).

Another embodiment of the disclosure includes the use of a foamed coreand/or the use of a hollow center of the core, which in both casessignificantly reduces the material required along the length of thefinished cable. The effect of foaming and/or producing asupport-separator with a hollow center portion should result in improvedflammability of the overall cable by reducing the amount of materialavailable as fuel for the UL 910 test, improved electrical propertiesfor the individual non-optical conductors, and reduction of weight ofthe overall cable.

A method and system wherein the blown and/or foamed perfluoropolymercomposition, cable, support-separator, conduit tube, insulation,jacketing, wrapping and/or taping line speeds are at or about 75 to 1500ft/min.

Additional benefits of the embodiments include reduction of the overallmaterial mass required for conventional spacers, insulation andjacketing which contributes to flame and smoke reduction.

Another embodiment of the disclosure includes the using this foamprocess, with either chemical or gas foaming, and placing the foam skinwith both being the same materials e.g.

(Perfluoropolymers) in a coextrusion or a second extrusion of athermoplastic non-fluoropolymer as a skin or encapsulated by a layer offoam or solid perfluoropolymer skin as an insulation, cable filler orjacket.

In an embodiment of the present disclosure it has been found that talc,generally known as a nucleating agent in foamed plastics, exhibitsblowing agent properties without the presence of a blowing agent.

Another embodiment combines talc, as a blowing agent, with resin(s) inthe absence of any additional chemical blowing agent wherein the talccomprises 2-50 percent by weight of the resin and wherein the resultingcomposition is extruded into an extrudate product.

In another embodiment the talc is combined with a resin as a masterbatchin a percentage of up to 15 percent talc by weight to resin and extrudedas a pellet.

In another embodiment the talc is combined with a recycled resin as amasterbatch in a percentage of up to 20 percent talc by weight torecycled resin and extruded as a pellet.

In another embodiment the resin(s) may be perfluoropolymers as a subsetof fluoropolymers FEP, MFA, PFA perfluoropolymers or semicrystallinefluoropolymers ECTFE, ETFE, PVDF, and PTFE, etc. as pure resin, recycledresin, as a single resin or in combination with other resins.

In yet another embodiment the extrudate is a pellet, insulation,jacketing, wire insulation.

In another embodiment the compounding pellet that is processed as anextrudate is sufficiently low temperature so that the fluoropolymerresin(s) are thermally constrained from foaming and subsequentlyextruded into jackets, separators, insulation, etc.

In another embodiment the pellets are extruded at a sufficiently hightemperature so that the resin is receptive to the talc blowing agentwherein the product is a foamed article.

In another embodiment the pellets may optionally include a colorconcentrate.

Another object of the disclosure is a foamed insulation comprising saidcomposition.

Still an object of the invention is a process for manufacturing thecomposition.

Still another object of the disclosure is a process for manufacturingfoamed insulation from the composition.

Other objects of the disclosure include recycled or waste materials toform these compositions (pelletized or otherwise), which can beprocessed and tumble blended with or without virgin or barefluoropolymers (such as perfluoropolymers) to obtain acceptable foamablecompositions after heating and extrusion.

Additionally it is known that foamed or blown articles or foamedcomposition produced with a gas blowing agent can be used in combinationwith talc leading to an increase in the percentage of cellular structurewithin a foamed or foamable composition when the combination of talc andeither a chemical or gas blowing agent is used. This works with the useof pellets that incorporate talc and where these pellets have beenformed when talc and fluorinated polymers form pelletized extrudate. Thepelletized extrudate (pellets) are then subsequently heated viaextrusion, molding, etc. to form the foamed, blown or cellular articlesof matter. These pellets are known as “foamable” pellets or foamablefluoropolymer compositions that may incorporate perfluoropolymers.

Additionally the pellets are suitable for foaming or blowing such thatwhen the pellets are combined with additional one or more selectedfluoropolymer (such as perfluoropolymers) in an amount of 7 weightpercent to 70 weight percent of the pellets to form an extrudate that isa foamed cellular insulation article.

Another embodiment is a method for manufacturing foamed or blownperfluoropolymer cellular insulation compositions wherein a secondcomposition is a blowing or foaming agent comprising 20 weight percentof the first composition and 80 weight percent of the selected one ormore perfluoropolymers heated to an appropriate melting point withhomogeneously blending, extruding, cooling and forming into pelletsusing chemical or gas injection methods.

Another embodiment is an extrusion process wherein extrusion of acomposition capable of forming cellular foam is extruded in an extruderwherein the extruder is specifically designed to minimize mechanicalshear and increased heating mitigating premature foaming during theprocess of melting, blending, extruding and pelletizing said compositionas well as mitigating corrosion of the extruder barrel due topassivation of acid and acidic gases provided by the use of talc withthe fluoropolymers (such as perfluoropolymers) during the extrusionprocess.

An additional embodiment is the perfluoropolymer compositions havingbeen added into an extruded melt of a base perfluoropolymer resin, insequential steps, sufficient talc to accomplish a loading of talc in arange of 0.5 to 20 percent in combination with perfluoropolymer resinforming compound pellets, wherein the compositions may be used forsubsequent heat extrusion or molding processes and provide cellular orfoamed or blown fluoropolymer (such as perfluoropolymer) end products.

In another embodiment the compounded pellets comprise 7.5 weight percenttalc and 92.5 weight percent perfluoropolymer resin.

The perfluoropolymer compositions may be extruded or molded into desiredshapes and geometries without pelletizing, wherein the talc is acting asa chemical blowing agent and may also act as a nucleating agent, afoaming agent or both during extrusion or molding.

The foamed cellular insulation article reduces the quantity ofcombustible materials by 30 to 60 percent based on the extent of thefoaming process, wherein the foamed cellular insulation article isachieved with or without a chemical blowing agent or gas blowing agent.

Another embodiment is a method of making a communications cable havingflame retardant properties comprising the steps of mixing the pellet(s)at a temperature of at most 600 degrees F. to ensure reaching themelting point of the fluoropolymer and melt processing the cablecompositions at predetermined temperatures exceeding 525 degrees F. toensure reaching the required temperature of the blowing agent, extrudinga metered amount of a melted composition around an advancing electricalconductor and allowing the composition to foam and expand to produce aninsulated conductor with a chemically blown perfluoropolymer insulation.

The pellets comprise 7.5 weight percent of said talc and 92.5 weightpercent of the fluoropolymer (such as perfluoropolymer).

The pellets comprise from 2 to 30 weight percent of said talc and 98 to70 weight percent of the fluoropolymer (such as perfluoropolymer).

The talc or talc derivative is a chemical composition of a magnesiumhydrosilicate represented by the formula; 3MgOSiO₂H₂O, wherein SiO₂ is63.5 percent weight, MgO is 31.90 percent weight and H₂O is 4.75 percentweight and optionally includes other minerals including magnesite,chlorite, calcite, magnetite, carbonate, and dolomite.

The pellets are chemically foamed or blown via an extrusion process, amolding process or any known process requiring heat and/or pressure toachieve a commercially viable cellular product(s).

The cellular product(s) include FEP, PFA and MFA, PTFE, ETFE, ECTFE orPVDF the resulting foamed extrudate of which comply with fire and smokeand sheathing requirements for LAN which may include electrical and/oroptical fiber conductors within the cable.

Included as an embodiment in the present application is a foamablecomposition, comprising;

-   -   at least one fluoropolymer, and;    -   a chemical agent capable of functioning as both a nucleating        agent and a foaming agent;    -   wherein the chemical agent constitutes the only foaming agent        present in the foamable composition.

An additional embodiment wherein the chemical agent is capable offunctioning as both a nucleating agent and a foaming agent of thefoamable composition and wherein the chemical agent allows forprocessing the foamable composition at a temperature of up to about 30degrees F. below conventional temperatures normally required duringextrusion of conventional foamable compositions having at least onefluoropolymer.

A further embodiment includes a foamable composition capable of beingcombined with an additional one or more fluoropolymers and thecombination is capable of being processed to form a foamed article.

An additional embodiment includes a foamable composition comprising; atleast one fluoropolymer, and; a foaming composition consistingessentially of one or more magnesium silicate compounds.

A further embodiment includes a foaming composition comprising: at leastone fluoropolymer in a molten state at an elevated temperature, and; achemical agent dispersed in the molten fluoropolymer, the chemical agentcapable of functioning as both a nucleating agent and a foaming agent;wherein the chemical agent constitutes the only foaming agent present inthe foaming composition and wherein the elevated temperature issufficient to cause said at least one chemical agent to foam.

A further embodiment includes an additional method of manufacturing afoamable composition is included herein comprising: forming a mixturecomprising a blend of a chemical agent capable of functioning as both anucleating agent and a foaming agent, and; at least one basefluoropolymer using thermal and mechanical energy at a processingtemperature below a temperature at which foaming of the mixture occurswherein the chemical agent constitutes the only foaming agent present inthe mixture, and processing the mixture to form a foamable composition.

As additional embodiment, included is the method for manufacturingfoamable perfluoropolymer cellular insulation compositions, wherein onecomposition includes up to 20 weight percent of a blowing or foamingagent and a second composition comprises up to 80 weight percent of oneor more selected perfluoropolymers heated to a melting point to assurehomogeneous blending, extruding, and cooling forming pellets thattogether with chemical or gas injection methods provide foamed articles.

Additionally, the method for manufacturing foamable fluoropolymercompositions include using organic or inorganic salt(s) together withone or more selected perfluoropolymers.

In a further embodiment, pellets are formed such that magnesiumcarbonate, calcium carbonate, or both magnesium carbonate and calciumcarbonate are added into forming a separate pellet in a tumble blendedmix or compounded together into a single homogenous pellet of talc and ablend of magnesium carbonate, calcium carbonate and Aclyn wax.

The same pellets may also include in their composition a colorconcentrate.

Additionally, another embodiment the insulation can be used for metal oroptical conductors including insulation forming a separator comprising;an inner core of a non-fluoropolymer or fluoropolymer and an outer layercovering the core comprising a foamed or foamed skinned perfluoropolymerwherein a cellular foaming extrusion process is performed using a singleor dual head extruder and wherein the cellular foam is formed bychemical means, gas injection means or both chemical and gas injectionmeans.

In an additional embodiment includes an extrusion process whereinextrusion of a composition capable of forming a cellular foamed articleis extruded in an extruder wherein the extruder is specifically designedto minimize mechanical shear and increase heating thereby mitigatingpremature foaming during the process of melting, blending, extruding,and pelletizing the composition as well as mitigating corrosion of theextruder barrel due to passivation of acid and acidic gases evolvingfrom the use of talc together with the perfluoropolymers andfluoropolymers during the extrusion process.

A further embodiment includes fluoropolymer compositions comprising;adding into an extruded melt of a base fluoropolymer resin, insequential steps, sufficient talc to accomplish a loading of talc in arange of 0.5 to 20 percent in combination with fluoropolymer resin toform pellets wherein the pellets are used for subsequent extrusion ormolding processes providing cellular, foamed, or blown fluoropolymer endproducts.

An additional embodiment includes compositions that are extruded ormolded into desired shapes and geometries without requiring pelletizing,wherein the talc acts as a chemical blowing agent and may also act as anucleating agent, a foaming agent, or both a nucleating and foamingagent during extrusion or molding processes.

The embodiment above wherein the talc neutralizes the acidity ofhydrogen fluoride and provides for lubricating and mitigating corrosionin extrusion barrels, screws, extrusion heads, tools and dies.

A further embodiment includes the use of talc significantly reduces theacidity of hydrogen fluoride during extrusion of the perfluoropolymercompositions.

An additional embodiment includes foamed cellular insulation articlesthat reduce the quantity of combustible materials by 30 to 60 percentbased on the extent of the foaming process and wherein cellular foamedinsulation articles are achieved with or without a chemical blowingagent or gas blowing agent.

The embodiment above wherein gas blowing agents are used in combinationwith talc leading to an increase in the percentage of cellular structurewithin the cellular foamed insulation article.

Another embodiment includes a method of making a communications cablehaving flame retardant properties comprising the steps of;

mixing the pellet(s) of the present application (any of those describedor contemplated) at a temperature of at most 600° F. to ensure reachingthe melting point of the polymer and melt processing the composition ata predetermined temperature exceeding 525° F. to ensure reaching therequired temperature for the blowing agent, extruding a metered amountof a melted composition around an advancing electrical conductor andallowing the composition to foam and expand to produce an insulatedconductor with a chemically blown perfluoropolymer insulation.

The embodiment above includes pellets comprising perfluoropolymers orfluoropolymers and a blowing agent consisting essentially of talc or anytalc derivative, wherein the talc or any talc derivative is a natural orsynthetic hydrated magnesium silicate.

Further to the latest two embodiments above, the talc or any talcderivative may be a chemical composition comprising magnesiumhydrosilicate represented by the formula; 3MgOSiO₂H₂O, wherein SiO₂ is63.5 weight percent MgO is 31.90 weight percent and H₂O is 4.75 weightpercent and can also include other minerals comprising; magnesite,chlorite, calcite, magnetite, carbonate, and dolomite.

A further embodiment includes cellular product(s) using one or more ofthe following; FEP, PFA MFA, PVDF, ECTFE, ETFE, and PTFE, the resultingfoamed extrudate of which comply with fire and smoke and sheathingrequirements for electrical or fiber optic cable.

Cellular material formed by heating pellets having a perfluoropolymerand a blowing agent consisting primarily of talc, to a temperature abovethe melting temperature of the perfluoropolymer, and above the requiredtemperature of the talc.

The cellular material is formed by heating the pellets during anextrusion process.

The disclosure includes and defines a cable utilizing the compositionsdescribed above.

DETAILED DESCRIPTION OF THE INVENTION

For the purpose of the present invention, the expressions“fluoropolymer” is intended to denote any polymer comprising recurringunits (R), with more than 25 weight percent of recurring units (R) beingderived from at least one ethylenically unsaturated monomer comprisingat least one fluorine atom (hereinafter, fluorinated monomer).

The fluoropolymer comprises preferably more than 30 weight percent morepreferably more than 40 percent weight of recurring units derived fromthe fluorinated monomer.

The fluorinated monomer can further comprise one or more other halogenatoms (Cl, Br, I). When the fluorinated monomer is free of a hydrogenatom, it is designated as per(halo)fluoromonomer. When the fluorinatedmonomer comprises at least one hydrogen atom, it is designated ashydrogen-containing fluorinated monomer.

Non limitative examples of fluorinated monomers are notablytetrafluoroethylene (TFE), vinylidene fluoride (VdF),chlorotrifluoroethylene (CTFE), and mixtures thereof.

Optionally, the fluoropolymer may comprise recurring units derived onefirst monomer, said monomer being a fluorinated monomer as abovedescribed, and at least one other monomer [comonomer (CM), hereinafter].

Hereinafter, the term comonomer (CM) should be intended to encompassboth one comonomer and two or more comonomers.

The comonomer (CM) can notably be either hydrogenated (i.e. free offluorine atom) [comonomer (HCM), hereinafter] or fluorinated (i.e.containing at least one fluorine atom) [comonomer (FCM), hereinafter].

Examples of suitable hydrogenated comonomers (HCM) are notably ethylene,propylene, vinyl monomers such as vinyl acetate, acrylic monomers, likemethyl methacrylate, acrylic acid, methacrylic acid and hydroxyethylacrylate, as well as styrene monomers, like styrene and p-methylstyrene.

In an embodiment of the invention, the polymer is a hydrogen-containingfluoropolymer. By “hydrogen-containing fluoropolymer” it is meant afluoropolymer as above defined comprising recurring units derived fromat least one hydrogen-containing monomer. A hydrogen-containing monomermay be the same monomer as the fluorinated monomer or can be a differentmonomer.

Thus, this definition encompasses notably copolymers of one or moreper(halo)fluoromonomers (for instance tetrafluoroethylene,chlorotrifluoroethylene, hexafluoropropylene, perfluoroalkylvinylethers,etc.) with one or more hydrogenated comonomer(s) (for instance ethylene,propylene, vinylethers, acrylic monomers, etc.), and/or homopolymers ofhydrogen-containing fluorinated monomers (for instance vinylidenefluoride, trifluoroethylene, vinyl fluoride, etc.) and their copolymerswith fluorinated and/or hydrogenated comonomers. The hydrogen-containingfluoropolymer are preferably chosen among:

-   -   TFE and/or CTFE copolymers with ethylene, propylene or        isobutylene (preferably ethylene), with a molar ratio        per(halo)fluoromonomer(s)/hydrogenated comonomer(s) of from        30:70 to 70:30, optionally containing one or more comonomers in        amounts of from 0.1 to 30 percent by moles, based on the total        amount of TFE and/or CTFE and hydrogenated comonomer(s) (see for        instance U.S. Pat. No. 3,624,250 and U.S. Pat. No. 4,513,129);    -   Vinylidene fluoride (VdF) polymers, optionally comprising        reduced amounts, generally comprised between 0.1 and 15 percent        by moles, of one or more fluorinated comonomer(s) (see for        instance U.S. Pat. No. 4,524,194 and U.S. Pat. No. 4,739,024),        and optionally further comprising one or more hydrogenated        comonomer(s);    -   and mixtures thereof.

As used here, a blowing agent comprising “primarily talc” achieves atleast most of its blowing function from talc. In certain exemplaryembodiments wherein the blowing agent comprises primarily talc, theblowing agent is at least 30 weight percent talc. That is, in suchembodiments talc is at least 30 weight percent of all materialsoperative as a blowing agent in the composition in the intendedextrusion or other forming operation. In certain exemplary embodimentsthe blowing agent is at least 10 weight percent talc. In certainexemplary embodiments the blowing agent is at least 20 weight percenttalc. In certain exemplary embodiments the blowing agent consistsessentially of talc. In certain exemplary embodiments talc is used incombination with other blowing agents, including, e.g., boron nitrideand/or other known blowing agents as well as any of the derivatives oftalc. Magnesium carbonate and calcium carbonate are additional chemicalagents that may used in combination with talc or any of the derivativesof talc.

Working Compounding Example 1

A composition including talc (MgSiOH; 3MgO+4SiO2+H2O; MgOH+H2O+SiOH) orother talc/talc derivatives such as Mg3Si4O10(OH)₂ is sequentially addedinto the feeder section with base perfluoropolymer resin in a ratio of15 percent-20 percent talc and 80 percent-85 percent perfluoropolymerresin. The extrusion of the base resin perfluoropolymer is pelletizedinto a single pellet. The temperature profile for zones 1 through 6would be as follows: 520, 530, 540, 560, 580 and 600 degrees Fahrenheit.The process temperatures of this single compound pellet with 7.5 percenttalc and 92.5 percent perfluoropolymer resin is kept to a minimum toensure no premature foaming occurs during pellet formation. The pelletsare then extruded on a 30 to 1 ratio high temperature extruder withtemperature zones of 525, 535, 550, 580, 640 and 660 degrees Fahrenheitfor the subsequent extrusion into profiles, insulations and jackets.

Working Insulation Extrusion Example 2

A foamed perfluoropolymer insulation was extruded over 24 gage wire byusing a cross head with a tip and die. The extruder was a hightemperature 1½ inch, 30:1 ratio device. The screw design was a 4:1 highcompression screw. The line speeds were in a range from 400 ft/min. to1500 ft/min. The screw rpm were from 12 rpm to 35 rpm with pressureranging from 1500 psi to 2000 psi. The melt temperature was 678 degreesF. The extruder was loaded with pellets containing 10 percent talc and90 percent FEP. This resulted in an insulation extrudate that was 41percent foamed with an average foamed cell size of 0.0007 inches.

Working Profile Extrusion Example 3

A cross web cable support-separator was manufactured with a 1½ inch hightemperature extruder using the following materials and conditions;

-   -   Use of a cross web die with a high compression screw, a line        speed of 148 ft./min. at a pressure of 1700 psi with a 48 RPM        screw speed and a melt temperature of 649 degrees F. The        extruder was loaded with a pellet master batch, the pellet        comprising 15 percent talc and 85 percent FEP. The pellet master        batch was blended in a 50:50 ratio with 100 percent FEP.        Therefore, the final blend ratio was 50 percent master batch        pellets and 50 percent FEP. This resulted in a cross web        extrudate that was 40 percent foamed with an average foamed cell        size of 0.0006 inches.

Working Profile Extrusion Example 4

A Double Helix cable support-separator was manufactured using a 1½ inchextruder with the following materials and conditions;

-   -   A web cable support-separator was manufactured using a profile        extrusion die with a high compression screw, a line speed of 75        ft./min. at a pressure of 1850 psi with a 40 RPM screw speed and        a melt temperature of 646 F. The extruder was loaded with master        batch pellets containing 15 percent talc and 85 percent FEP.        This master batch was blended with 100 percent FEP. The final        blend ratio was 70 percent master batch pellets and 30 percent        FEP. This resulted in a web extrudate that was 33 percent foamed        with an average foamed cell size of 0.0007 inches.

Working Insulation Extrusion Example 5

A foamed perfluoropolymer insulation was extruded over 24 gage wire byusing a cross head with a tip and die. The extruder was a hightemperature 1½ inch, 30:1 ratio device. The screw design was a 4:1 highcompression screw. The line speeds were in a range from 300 ft/min. to900 ft/min. The screw rpm were from 12 rpm to 30 rpm with pressureranging from 1500 psi to 2000 psi. The melt temperature was 680 F. Theextruder was loaded with pellets containing 10 percent talc and 90percent FEP. This resulted in an insulation extrudate that was 35percent foamed with an average foamed cell size of 0.0007 inches.

Other desired embodiments, results, and novel features of the presentinvention will become more apparent from the following drawings,detailed description of the drawings, and the accompanying claims.

DETAILED DESCRIPTIONS

The following description will further help to explain the inventivefeatures of the system, method and composition of the presentdisclosure.

The composition is comprised of magnesium silicate hydroxide, commonlyknown as talc and perfluoropolymer. The ratio of talc is at or about 15percent with the perfluoropolymer at or about 85 percent by weight,however the talc may range in concentration from 0.2 to 20 percent andup to 50%. The perfluoropolymer component of the composition may be MFA,FEP, PFA, or ETFE, as a selected, uniform, pure fluoropolymer (such asperfluoropolymer) or as a mixture of one or more differentfluoropolymers (such as perfluoropolymers) or 100 percent recycledand/or blended with non-recycled perfluoropolymers in any ratio from 1to 99 percent. The composition is then placed in an extruderspecifically designed to minimize heat transfer such that foaming ornucleation is not prematurely initiated and such that the compositionmay be melted, blended, extruded and pelletized. Additionally, anorganic or inorganic salt may be added to the pellet composition.

The composition may also comprise inorganic and/or organic additivesthat include inorganic salts, metallic oxides, silica and silicon oxidesas well as substituted and unsubstituted fullerenes.

The pellet composition may then be blended with virgin or recycledfluorinated polymers, fluoropolymers (such as perfluoropolymers),extruded at a temperature higher than the foaming or nucleationtemperature so that foaming and nucleation occur in the fluorinatedpolymers.

It will, of course, be appreciated that the system, method andcompositions that have been described have been given simply by the wayof illustration, and the disclosure is not limited to the preciseembodiments described herein; various changes and modifications may beeffected by one skilled in the art without departing from the scope orspirit of the invention as defined in the inventive claims.

What is claimed is: 1-217. (canceled)
 218. A foamable composition,comprising: at least one fluoropolymer, and; a chemical agent capable offunctioning as both a nucleating agent and foaming agent.